This invention relates to a broaching machine utilized for carrying out a broaching operation.
In a conventional art, a broaching machine using a rotary-type broaching tool for carrying out a broaching operation is provided with a pair of opposing broaching units in which both ends of a broaching shaft disposed at a central portion of the broaching tool are supported by a drive shaft and a support shaft respectively provided for the paired broaching units, and one end of the broaching shaft and the drive shaft and the other end of the broaching shaft and the support shaft are coupled together, respectively, by means of bolts.
Because of this coupling, when it is required to exchange the broaching tool, it is necessary to entirely disassemble the broaching tool by removing the bolts or to disassemble the broaching tool from the broaching shaft with the broaching shaft remaining as it is, and thereafter, to exchange the removed broaching tool with a new one, thus requiring much time and labor for such an exchanging operation, thereby resulting in efficiency.
Furthermore, there is known a conventional machine in which a plurality of segments are fixed to an outer peripheral portion of a body of a broaching tool, for example, as disclosed in Japanese Utility Model Laid-open Publication No. HEI 4-5313 or Japanese Patent Laid-open Publication No. HEI 2-145207.
In the machine of the former publication, a press piece being rotatably fitted to a clamp bolt screwed with a broaching tool body and entirely penetrating an elongate hole of a segment is rotated by 90.degree. to be engaged with the segment, and under this condition, the clamp bolt is tightened so that the segment is fixed to the broaching tool body.
On the other hand, the machine of the latter publication is provided with a holder to which a segment is fixed, and the segment is fixed to the broaching tool through the holder by rotating a T-bolt having a head penetrating an elongate hole of the holder and a shank screwed with the broaching tool body so that the head is engaged with the holder.
However, both the segment fixing machines of the above prior arts are not provided with any means for limiting the rotation of the press piece and the T-bolt at predetermined positions, so that, when the clamp bolt or T-bolt is loosened to remove the segment from the broaching tool, the position of the press piece or T-bolt is not determined, and hence, the segment is interfered with by the pressure piece or the head of the T-bolt, thus making it difficult to remove the segment, which also results in much time and labor for the exchanging of the tool, thereby resulting in poor efficiency.
Furthermore, in the former machine, a spring means interposed between the press piece and the broaching tool body is fitted to the clamp bolt, but in such structure, cut chips and the like are liable to adhere to the spring after the removal of the segment, so that the cut chips adhering to the spring intrude into a portion, for example, between the segment and the press piece, which may damage the segment, and there is a fear of deforming the bolt by a bending force applied to the bolt at the tightening time, whereby it becomes impossible to clamp the bolt with the sufficient torque.